Familial aggregation of submaximal aerobic performance in the HERITAGE Family study

Purpose: This study examines the contribution of genetic factors to submaxi mal aerobic performance phenotypes measured before and after 20 wk of endur ance training. Methods: Submaximal oxygen consumption (((V) over dot )O-2) at three power outputs, 50 W (((V) over dot)O(2)50W), 60% (((V) over dot)O( 2)60%) and 80% (((V) over dot)O(2)80%) of ((V) over dot)O-2max and power ou tputs at 60% (PO60%) and 80% (PO80%) of ((V) over dot )O-2max were measured during cycle ergometer exercise tests in 483 subjects from 99 white famili es participating in the HERITAGE Family study. The baseline phenotypes were adjusted for the effects of age, sex, and body mass using stepwise multipl e regression procedures. The response phenotypes, computed as the differenc e (Delta) between the posttraining and baseline measures, were adjusted for age, sex, and the baseline value. Results: All submaximal exercise phenoty pes measured at baseline and in response to training were characterized by a significant familial resemblance. Maximal heritabilities of the baseline phenolypes range from 48% to 74% with significant spouse, sibling, and pare nt-offspring correlations. The hypothesis of maternal inheritance where mot her-offspring and sibling correlations were forced to be equal was found to fit the data for ((V) over dot)O(2)60%, ((V) over dot)O(2)80% and PO80%. F or the response phenotypes, the maximal heritabilities tended to be lower ( 23-57%) with a significant maternal inheritance for Delta((V) over dot)O(2) 60%, Delta PO60%, and Delta PO80%. Conclusion: These results suggest that t he submaximal working capacities of sedentary subjects and their responses to endurance training are influenced by familial/genetic factors with a sig nificant contribution of maternal inheritance.